Information transmission method and apparatus

ABSTRACT

Embodiments of this application provide an information transmission method and an apparatus, to improve transmission reliability. The method includes: obtaining, by a terminal device, a to-be-sent pilot sequence, where the to-be-sent pilot sequence is a Reed-Muller sequence; and sending, by the terminal device, the to-be-sent pilot sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2017/086033, filed on May 26, 2017, which claims priority toChinese Patent Application No. 201610368154.5, filed on May 27, 2016.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and morespecifically, to an information transmission method and an apparatus.

BACKGROUND

In a typical wireless communications network (for example, Long TermEvolution (LTE)), selection of an uplink shared channel is based on ascheduling/grant mechanism and is completely controlled by a basestation (BS). In the mechanism, user equipment (UE) first sends anuplink scheduling request to the BS. After receiving the request, the BSsends an uplink grant to the UE, to inform the UE of an uplinktransmission resource allocated to the UE. Accordingly, the UE transmitsdata on the granted uplink transmission resource.

Massive user access is one of typical application scenarios of anext-generation communications network. During massive user access,using the foregoing scheduling/grant mechanism not only causes enormoussignaling transmission overheads and resource allocation schedulingpressure of a BS, but also results in a considerable transmissionlatency. In view of this, the next-generation communications networkuses a grant-free transmission mode to support massive user access.

In the foregoing grant-free transmission for massive user access,because a plurality of UEs are allowed to perform contention-basedtransmission on a same time-frequency resource, a contention-causedcollision occurs, thereby reducing grant-free transmission reliability.

SUMMARY

Embodiments of this application provide an information transmissionmethod, a terminal device, a network device, and a storage medium, toimprove transmission reliability.

According to a first aspect, an information transmission method isprovided, including: obtaining, by a terminal device, a to-be-sent pilotsequence, where the to-be-sent pilot sequence is a Reed-Muller sequence;and sending, by the terminal device, the to-be-sent pilot sequence.

With reference to the first aspect, in a first possible implementationof the first aspect, the method is applied to grant-free transmission.

In this application, a pilot sequence is implemented by using aReed-Muller sequence. In this way, a large quantity of sequences can begenerated, and different sequences are closely correlated. Therefore,grant-free transmission reliability can be improved.

With reference to the first aspect or the first possible implementationof the first aspect, in a second possible implementation of the firstaspect, the to-be-sent pilot sequence is generated according to aReed-Muller sequence generation formula.

With reference to the second possible implementation of the firstaspect, in a third possible implementation of the first aspect, theto-be-sent pilot sequence is an order-2 Reed-Muller sequence generatedaccording to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2\; b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2m and m is a positive integer;p is a matrix of m rows and m columns; b is a vector of m rows; a is abit vector with a length of m and consisting of 0s and 1s, has a totalof 2^(m) possible values, and is corresponding to 2^(m) elements of thepilot sequence; and i²=−1.

Optionally, when a Reed-Muller sequence is generated according to theorder-2 sequence generation formula, a value of p may be 0.

With reference to any one of the first aspect or the foregoing possibleimplementations of the first aspect, in a fourth possible implementationof the first aspect, the obtaining, by a terminal device, a to-be-sentpilot sequence is specifically: obtaining, by the terminal device, theto-be-sent pilot sequence from a pilot sequence set, where the pilotsequence set includes at least two Reed-Muller sequences.

The to-be-sent pilot sequence may be selected from the pilot sequenceset randomly or based on a pilot index. For example, the pilot index maybe generated by using a random number generator. For example, differentinitial values may be set for a pseudo-noise (Pseudo-noise, PN) sequenceto generate different random number sequences, so that the pilot indexis obtained accordingly. A possible method for selecting the initialvalue is based on at least one of an identifier of the terminal, asystem frame number, a timeslot number, and a cell identifier. Thesystem frame number may be a sequence number of a frame in which atarget pilot sequence is to be transmitted, the timeslot number may be anumber of a timeslot in which the target pilot sequence is to betransmitted, and the cell identifier may be an identifier of a cell inwhich the terminal device is located.

With reference to the third possible implementation of the first aspect,in a fifth possible implementation of the first aspect, the obtaining,by a terminal device, a to-be-sent pilot sequence is specifically:determining the length of the to-be-sent pilot sequence, where thelength of the to-be-sent pilot sequence is 2^(m) and m is a positiveinteger; determining the matrix p of m rows and m columns and the vectorb of m rows; and generating an order-2 Reed-Muller sequence as theto-be-sent pilot sequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2\; b} + {pb}})}^{T}a}.}}$

With reference to the fifth possible implementation of the first aspect,in a sixth possible implementation of the first aspect, before theobtaining, by a terminal device, a to-be-sent pilot sequence, the methodfurther includes: receiving, by the terminal device, first indicationinformation sent by a network device, where the first indicationinformation is used to indicate the length of the to-be-sent pilotsequence; and the determining the length of the to-be-sent pilotsequence is specifically: determining the length of the to-be-sent pilotsequence based on indication of the first indication information.

Optionally, different pilot sequence lengths may be corresponding tosets having different quantities of elements. In other words, a matrix pset and a vector b set may be determined based on a pilot sequencelength, and the matrix p and the vector b may be selected from thematrix p set and the vector b set, respectively.

With reference to the fifth possible implementation of the first aspect,in a seventh possible implementation of the first aspect, thedetermining the length of the to-be-sent pilot sequence is specifically:determining the length of the to-be-sent pilot sequence based on a sizeof a to-be-used time-frequency resource.

With reference to any one of the fifth to the seventh possibleimplementations of the first aspect, in an eighth possibleimplementation of the first aspect, the matrix p is a binary symmetricmatrix.

With reference to any one of the fourth to the eighth possibleimplementations of the first aspect, in a ninth possible implementationof the first aspect, the determining the matrix p of m rows and mcolumns and the vector b of m rows is specifically: selecting the matrixp from a matrix p set corresponding to m; and selecting the vector bfrom a vector b set corresponding to m.

The matrix p set includes a plurality of matrices p of m rows and mcolumns. The vector b of m rows may be selected from the vector b set,where the vector b set includes a plurality of vectors b of m rows.

With reference to the ninth possible implementation of the first aspect,in a tenth possible implementation of the first aspect, the matrix p inthe matrix p set is a binary symmetric matrix whose diagonal consists of0s, and each element of the matrix p is 0 or 1; and/or the vector b inthe vector b set is a binary vector, and each element of the vector b is0 or 1.

With reference to the ninth or the tenth possible implementation of thefirst aspect, in an eleventh possible implementation of the firstaspect, the method further includes: generating a pilot index based onat least one of an identifier of the terminal device, a system framenumber, a timeslot number, and a cell identifier; the selecting thematrix p is specifically: selecting, based on the pilot index, thematrix p from the matrix p set corresponding to m; and the selecting thevector b is specifically: selecting, based on the pilot index, thevector b from the vector b set corresponding to m.

With reference to any one of the ninth to the eleventh possibleimplementations of the first aspect, in a twelfth possibleimplementation of the first aspect, the method further includes:receiving, by the terminal device, second indication information sent bythe network device, where the second indication information is used toindicate the matrix p set and/or the vector b set, so that based onindication of the second indication information, the terminal device canselect the matrix p from the matrix p set indicated by the secondindication information, and select the vector b from the vector b setindicated by the second indication information.

According to a second aspect, an information transmission method isprovided, including: obtaining, by a network device, a received signal,where the received signal includes a pilot sequence of at least oneterminal device, and the pilot sequence is a Reed-Muller sequence; andobtaining the pilot sequence of the at least one terminal device fromthe received signal.

With reference to the second aspect, in a first possible implementationof the second aspect, the pilot sequence is an order-2 Reed-Mullersequence generated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2\; b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.

With reference to the second aspect or the foregoing possibleimplementation of the second aspect, in a second possible implementationof the second aspect, before the obtaining, by a network device, areceived signal, the method further includes: sending, by the networkdevice, first indication information to the terminal device, where thefirst indication information is used to indicate a length of ato-be-sent pilot sequence.

With reference to any one of the second aspect or the foregoing possibleimplementations of the second aspect, in a third possible implementationof the second aspect, before the obtaining, by a network device, areceived signal, the method further includes: sending, by the networkdevice, second indication information to the terminal device, where thesecond indication information is used to indicate a vector b set and amatrix p set, the vector b set is used by the terminal device to selectthe vector b, and the matrix p set is used by the terminal device toselect the matrix p, so that based on indication of the secondindication information, the terminal device can select the matrix p fromthe matrix p set indicated by the second indication information, andselect the vector b from the vector b set indicated by the secondindication information.

With reference to any one of the second aspect or the foregoing possibleimplementations of the second aspect, in a fourth possibleimplementation of the second aspect, the method further includes:detecting, based on a pilot sequence of each terminal device, data sentby the terminal device; and sending an acknowledgment feedback messageto the terminal device when the data is successfully decoded; or sendinga negative acknowledgment feedback message to the terminal device whenthe data is unsuccessfully decoded.

According to a third aspect, an information transmission method isprovided, where the method includes: obtaining, by a terminal device, ato-be-sent pilot sequence, where the to-be-sent pilot sequence is asequence generated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2\; b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1; and sending, by the terminal device,the to-be-sent pilot sequence.

With reference to the third aspect, in a first possible implementationof the third aspect, the terminal device obtains the to-be-sent pilotsequence from a pilot sequence set, where the pilot sequence setincludes at least two sequences.

With reference to the third aspect or the foregoing possibleimplementation of the third aspect, in a second possible implementationof the third aspect, the length of the to-be-sent pilot sequence isdetermined, where the length of the to-be-sent pilot sequence is 2^(m)and m is a positive integer; the matrix p of m rows and m columns andthe vector b of m rows are determined; and a sequence is generated asthe to-be-sent pilot sequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

With reference to any one of the third aspect or the foregoing possibleimplementations of the third aspect, in a third possible implementationof the third aspect, first indication information sent by a networkdevice is received, where the first indication information is used toindicate the length of the to-be-sent pilot sequence; and the length ofthe to-be-sent pilot sequence is determined based on indication of thefirst indication information.

With reference to any one of the third aspect or the foregoing possibleimplementations of the third aspect, in a fourth possible implementationof the third aspect, the terminal device selects the matrix p from amatrix p set corresponding to m, and selects the vector b from a vectorb set corresponding to m.

With reference to any one of the third aspect or the foregoing possibleimplementations of the third aspect, in a fifth possible implementationof the third aspect, the matrix in the matrix p set is a binarysymmetric matrix whose diagonal consists of 0s, and each element of thematrix is 0 or 1; and/or the vector in the vector b set is a binaryvector, and each element of the vector is 0 or 1.

With reference to any one of the third aspect or the foregoing possibleimplementations of the third aspect, in a sixth possible implementationof the third aspect, a pilot index is generated based on at least one ofan identifier of the terminal device, a system frame number, a timeslotnumber, and a cell identifier; based on the pilot index, the matrix p isselected from the matrix p set corresponding to m; and based on thepilot index, the vector b is selected from the vector b setcorresponding to m.

With reference to any one of the third aspect or the foregoing possibleimplementations of the third aspect, in a seventh possibleimplementation of the third aspect, second indication information sentby the network device is received, where the second indicationinformation is used to indicate the matrix p set and/or the vector bset.

According to a fourth aspect, an information transmission method isprovided, where the method includes: obtaining a received signal, wherethe received signal includes a pilot sequence sent by at least oneterminal device, and the pilot sequence is a sequence generatedaccording to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1; and obtaining the pilot sequence sentby the at least one terminal device from the received signal.

With reference to the fourth aspect, in a first possible implementationof the fourth aspect, a network device sends first indicationinformation to the terminal device, where the first indicationinformation is used to indicate a length of a to-be-sent pilot sequence.

With reference to the fourth aspect or the first possible implementationof the fourth aspect, in a second possible implementation of the fourthaspect, the network device sends second indication information to theterminal device, where the second indication information is used toindicate a vector b set and a matrix p set, the vector b set is used bythe terminal device to select the vector b, and the matrix p set is usedby the terminal device to select the matrix p.

According to a fifth aspect, a terminal device is provided, configuredto perform the method according to any one of the first aspect or thepossible implementations of the first aspect. Specifically, the terminaldevice includes modules or units configured to perform the methodaccording to any one of the first aspect or the possible implementationsof the first aspect.

According to a sixth aspect, a network device is provided, configured toperform the method according to any one of the second aspect or thepossible implementations of the second aspect. Specifically, the networkdevice includes modules or units configured to perform the methodaccording to any one of the second aspect or the possibleimplementations of the second aspect.

According to a seventh aspect, a terminal device is provided, configuredto perform the method according to any one of the third aspect or thepossible implementations of the third aspect. Specifically, the terminaldevice includes modules or units configured to perform the methodaccording to any one of the third aspect or the possible implementationsof the third aspect.

According to an eighth aspect, a network device is provided, configuredto perform the method according to any one of the fourth aspect or thepossible implementations of the fourth aspect. Specifically, the networkdevice includes modules or units configured to perform the methodaccording to any one of the fourth aspect or the possibleimplementations of the fourth aspect.

According to a ninth aspect, a terminal device is provided, including amemory and a processor, where the memory is configured to store aninstruction; the processor is configured to execute the instructionstored in the memory; and when the processor executes the instructionstored in the memory, the execution causes the processor to perform themethod according to any one of the first aspect or the possibleimplementations of the first aspect.

According to a tenth aspect, a network device is provided, including amemory and a processor, where the memory is configured to store aninstruction; the processor is configured to execute the instructionstored in the memory; and when the processor executes the instructionstored in the memory, the execution causes the processor to perform themethod according to any one of the second aspect or the possibleimplementations of the second aspect.

According to an eleventh aspect, a terminal device is provided,including a memory and a processor, where the memory is configured tostore an instruction; the processor is configured to execute theinstruction stored in the memory; and when the processor executes theinstruction stored in the memory, the execution causes the processor toperform the method according to any one of the third aspect or thepossible implementations of the third aspect.

According to a twelfth aspect, a network device is provided, including amemory and a processor, where the memory is configured to store aninstruction; the processor is configured to execute the instructionstored in the memory; and when the processor executes the instructionstored in the memory, the execution causes the processor to perform themethod according to any one of the fourth aspect or the possibleimplementations of the fourth aspect.

According to a thirteenth aspect, a computer storage medium is provided,where the computer storage medium stores program code, and the programcode is used to instruct to perform the method according to any one ofthe first aspect or the possible implementations of the first aspect.

According to a fourteenth aspect, a computer storage medium is provided,where the computer storage medium stores program code, and the programcode is used to instruct to perform the method according to any one ofthe second aspect or the possible implementations of the second aspect.

According to a fifteenth aspect, a computer storage medium is provided,where the computer storage medium stores program code, and the programcode is used to instruct to perform the method according to any one ofthe third aspect or the possible implementations of the third aspect.

According to a sixteenth aspect, a computer storage medium is provided,where the computer storage medium stores program code, and the programcode is used to instruct to perform the method according to any one ofthe fourth aspect or the possible implementations of the fourth aspect.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of an application scenario according to anembodiment of this application;

FIG. 2 is a schematic diagram of a Reed-Muller sequence according to anembodiment of this application;

FIG. 3 is a schematic flowchart of an information transmission methodaccording to an embodiment of this application;

FIG. 4 is a diagram of time-frequency resource utilization according toan embodiment of this application;

FIG. 5 is a schematic flowchart of an information transmission methodaccording to an embodiment of this application;

FIG. 6 is a schematic flowchart of an information transmission methodaccording to an embodiment of this application;

FIG. 7 is a schematic block diagram of a terminal device according to anembodiment of this application;

FIG. 8 is a schematic block diagram of a network device according to anembodiment of this application;

FIG. 9 is a schematic block diagram of a terminal device according to anembodiment of this application;

FIG. 10 is a schematic block diagram of a network device according to anembodiment of this application;

FIG. 11 is a schematic block diagram of a terminal device according toan embodiment of this application;

FIG. 12 is a schematic block diagram of a network device according to anembodiment of this application;

FIG. 13 is a schematic block diagram of a terminal device according toan embodiment of this application; and

FIG. 14 is a schematic block diagram of a network device according to anembodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes the technical solutions in the embodiments ofthis application with reference to the accompanying drawings in theembodiments of this application.

The terms such as “component”, “module”, and “system” used in thisspecification are used to indicate computer-related entities, hardware,firmware, combinations of hardware and software, software, or softwarebeing executed. For example, a component may be but is not limited to aprocess that runs on a processor, a processor, an object, an executablefile, a thread of execution, a program, and/or a computer. As shown infigures, both a computing device and an application that runs on acomputing device may be components. One or more components may residewithin a process and/or a thread of execution, and a component may belocated on one computer and/or distributed between two or morecomputers. In addition, these components may be executed from variouscomputer-readable media that store various data structures. For example,the components may communicate by using a local and/or remote processand according to, for example, a signal having one or more data packets(for example, data from one component interacting with another componentin a local system, a distributed system, and/or across a network such asthe Internet interacting with other systems by using the signal).

It should be understood that, the technical solutions in the embodimentsof this application may be applied to various communications systems,for example, a Global System for Mobile Communications (GSM) system, aCode Division Multiple Access (CDMA) system, a Wideband Code DivisionMultiple Access (WCDMA) system, a Long Term Evolution (LTE) system, anLTE frequency division duplex (FDD) system, an LTE time division duplex(TDD) system, a Universal Mobile Telecommunications System (UMTS), and afuture 5G communications system.

This application describes the embodiments with reference to a terminaldevice. The terminal device may also be referred to as user equipment(UE), an access terminal, a subscriber unit, a subscriber station, amobile station, a mobile console, a remote station, a remote terminal, amobile device, a user terminal, a terminal, a wireless communicationsdevice, a user agent, or a user apparatus. The access terminal may be acellular phone, a cordless telephone set, a Session Initiation Protocol(SIP) phone, a wireless local loop (WLL) station, a personal digitalassistant (PDA), a handheld device having a wireless communicationfunction, a computing device, another processing device connected to awireless modem, an in-vehicle device, a wearable device, a terminaldevice in a future 5G network, a terminal device in a future evolvedPLMN network, or the like.

This application describes the embodiments with reference to a networkdevice. The network device may be a device configured to communicatewith a terminal device. For example, the network device may be a basetransceiver station (BTS) in a GSM system or CDMA, may be a NodeB (NB)in a WCDMA system, or may be an evolved NodeB (eNB or eNodeB) in an LTEsystem. Alternatively, the network device may be a relay node, an accesspoint, an in-vehicle device, a wearable device, a network-side device ina future 5G network, or a network device in a future evolved PLMNnetwork.

Due to existence of a large quantity of connections, there is asignificant difference between a future wireless communications systemand an existing communications system. Because of the large quantity ofconnections, more resources need to be consumed for UE access, and moreresources need to be consumed for scheduling signaling transmissionrelated to data transmission of a terminal device.

FIG. 1 is a schematic architecture diagram of a communications system towhich an embodiment of this application is applied. As shown in FIG. 1,the communications system 100 may include a network device 102 andterminal devices 104 to 114 (referred to as UE for short in the figure).The network device 102 and the terminal devices 104 to 114 are connectedin a wireless manner, a wired manner, or another manner.

A network in this embodiment of this application may be a public landmobile network (PLMN), a D2D network, an M2M network, or anothernetwork. FIG. 1 is merely an example of a simplified schematic diagram.The network may further include another network device that is not shownin FIG. 1.

This application proposes a grant-free transmission solution. Thegrant-free transmission can adapt to a large quantity of MTC-typeservices in a future network and satisfy ultra-reliable and low-latencyservice transmission. The grant-free transmission may be used for uplinkdata transmission. A person skilled in the art can know that thegrant-free transmission may have other names, such as spontaneousaccess, spontaneous multiple access, or contention-based multipleaccess. The grant-free transmission may be understood as including butnot limited to any one or more of the following meanings, or acombination of some technical features in a plurality of the followingmeanings.

1. The grant-free transmission may mean: A network device pre-allocatesa plurality of transmission resources to a terminal device and informsthe terminal device of the plurality of transmission resources; when theterminal device has an uplink data transmission requirement, theterminal device selects at least one transmission resource from theplurality of transmission resources pre-allocated by the network device,and sends uplink data by using the selected transmission resource; andthe network device detects, on one or more of the plurality ofpre-allocated transmission resources, the uplink data sent by theterminal device. The detection may be blind detection, detection that isperformed based on a control field in the uplink data, or detectionperformed in another manner.

2. The grant-free transmission may mean: A network device pre-allocatesa plurality of transmission resources to a terminal device and informsthe terminal device of the plurality of transmission resources, so thatwhen the terminal device has an uplink data transmission requirement,the terminal device selects at least one transmission resource from theplurality of transmission resources pre-allocated by the network device,and sends uplink data by using the selected transmission resource.

3. The grant-free transmission may mean: Information about a pluralityof pre-allocated transmission resources is obtained; and when there isan uplink data transmission requirement, at least one transmissionresource is selected from the plurality of transmission resources, anduplink data is sent by using the selected transmission resource. Anobtaining manner may be obtaining the information about a plurality ofpre-allocated transmission resources from a network device.

4. The grant-free transmission may mean: A method for transmittinguplink data by a terminal device can be implemented without dynamicscheduling by a network device, where the dynamic scheduling may be ascheduling manner in which the network device indicates, by usingsignaling, a transmission resource for each uplink data transmission ofthe terminal device. Optionally, implementing uplink data transmissionof a terminal device can be understood as follows: At least two terminaldevices are allowed to perform uplink data transmission on a sametime-frequency resource. Optionally, the transmission resource may be atransmission resource of one or more transmission time units following amoment at which the UE receives the signaling. A transmission time unitmay be a smallest time unit for one transmission, for example, atransmission time interval (Transmission Time Interval, TTI), where avalue may be 1 ms; or a transmission time unit may be a presettransmission time unit.

5. The grant-free transmission may mean: A terminal device performsuplink data transmission without granting from a network device. Thegranting may mean: The terminal device sends an uplink schedulingrequest to the network device; and after receiving the schedulingrequest, the network device sends an uplink grant to the terminaldevice, where the uplink grant indicates an uplink transmission resourceallocated to the terminal device.

6. The grant-free transmission may mean a contention-based transmissionmode, and may specifically mean: A plurality of terminals perform uplinkdata transmission on a same pre-allocated time-frequency resourcesimultaneously without granting from a network device.

The data may include service data or signaling data.

The blind detection may be understood as detecting possibly arrivingdata when data arrival is unknown in advance. The blind detection mayalso be understood as detection without an explicit signalingindication.

The transmission resource may include but is not limited to one or acombination of the following resources: a time-domain resource, such asa radio frame, a subframe, and a symbol; a frequency-domain resource,such as a subcarrier and a resource block; a space-domain resource, suchas a transmit antenna and a beam; a code-domain resource, such as aSparse Code Multiple Access (SCMA) codebook set, a Low Density Signature(LDS) set, and a CDMA code set; and an uplink pilot resource.

The foregoing transmission resource may be used for transmissionperformed by using a control mechanism including but not limited to thefollowing: uplink power control, such as controlling an upper limit ofuplink transmit power; modulation and coding scheme setting, such assetting a transport block size, a code rate, and a modulation order; anda retransmission mechanism, such as a HARQ mechanism.

It should be further understood that, in the embodiment of FIG. 1, anexample in which the network device is a base station is used fordescription, and the network device may alternatively be another accessdevice (such as a radio access point).

For ease of understanding of this application, the terms in theembodiments of this application are described below.

One bottleneck problem of grant-free transmission is a quantity ofpilots. If there is a relatively small quantity of pilots, users cannotbe distinguished by using the pilots, and the users need to share thepilots. In addition, when a pilot collision occurs, a base stationcannot perform accurate user detection or channel estimation, and cannotsuccessfully demodulate data.

In the embodiments of this application, grant-free transmission may meangrant-free multiple access, and may be referred to as autonomousmultiple access, contention-based multiple access, or the like.

Therefore, in the embodiments of this application, a Reed-Mullersequence is proposed to implement a pilot sequence. Certainly, a personskilled in the art knows that the Reed-Muller sequence may have anothername. The Reed-Muller sequence may be a sequence generated from one ormore sets of Reed-Muller codes. According to this manner of generating aReed-Muller sequence, a large quantity of sequences can be generated,different sequences are closely correlated, and complexity of sequencedetection can be considerably reduced by using a fast reconstructionalgorithm. It should be understood that, implementing a pilot sequenceby using a Reed-Muller sequence in this embodiment of this applicationcan be used for not only grant-free transmission but also anothertransmission scenario.

The following describes a Reed-Muller sequence generation manner.

1. An order-1 function used for generating a Reed-Muller sequence may bedefined as:

$\begin{matrix}{{{\varphi_{b}(a)} = {\frac{1}{\sqrt{2^{m}}}\left( {- 1} \right)^{b^{T}a}}},} & {{formula}\mspace{20mu} 1}\end{matrix}$

where

2^(m) is a sequence length, a and b are each a bit vector of a length m,and b^(T)a indicates a vector inner product. When b is provided, asequence of a length 2^(m) may be obtained by traversing all possiblea's. A column of a matrix H shown in FIG. 2 is referred to as a sequence(which may also be referred to as a codeword). Because b has 2^(m)possible values, there are 2^(m) different sequences. It can be proventhat 2^(m) sequences generated by the order-1 Reed-Muller function areorthogonal to each other, and constitute a group of orthogonal bases ofvector space of a length m.

2. An order-2 function used for generating a Reed-Muller sequence may bedefined as:

$\begin{matrix}{{{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},} & {{formula}\mspace{20mu} 2}\end{matrix}$

where

p is a matrix of m rows and m columns, a and b are each a bit vector ofa length m, and i²=−1. Herein, all elements of p, a, and b are 0s or 1s.When p and b are provided, a codeword having 2^(m) elements, that is, asequence, may be generated. There are a total of 2^(m(m-1)/2) differentp's and 2^(m) different b's, and a total of 2^(m(m-1)/2) sequences maybe generated. Therefore, a large quantity of pilot sequences may beprovided, to meet a requirement of massive access.

Optionally, the matrix p may be selected from a matrix p set and thevector b may be selected from a vector b set.

Optionally, different pilot sequence lengths may be corresponding tosets having different quantities of elements. In other words, a matrix pset and a vector b set may be determined based on a pilot sequencelength, and the matrix p and the vector b may be selected from thematrix p set and the vector b set, respectively.

Optionally, the matrix in the matrix p set is a binary symmetric matrixwhose diagonal consists of 0s, and each element of the matrix is 0 or 1.In this case, a function value obtained by using the foregoing formula 2is a real number.

Optionally, the vector in the vector b set is a binary vector, and eachelement of the vector is 0 or 1.

It should be understood that, when a Reed-Muller sequence is generatedaccording to the order-2 formula, if p=0, the order-2 formula isequivalent to the foregoing order-1 formula. In other words, variousoptional solutions used for generating a pilot sequence based on theorder-2 formula in this embodiment of this application are alsoapplicable to a case in which a pilot sequence is generated by using theorder-1 formula.

It should be understood that, the pilot sequence may alternatively beobtained by using a Reed-Muller function of a higher order.

The foregoing details a Reed-Muller sequence mentioned in theembodiments of this application. The following describes how to performpilot transmission according to an embodiment of this application withreference to a method 200 shown in FIG. 3. Optionally, the method 200may be applied to grant-free transmission, and may also be applied toanother scenario.

Step 210: A terminal device obtains a to-be-sent pilot sequence, wherethe to-be-sent pilot sequence is a Reed-Muller sequence.

Optionally, in this embodiment of this application, the to-be-sent pilotsequence may be generated according to a Reed-Muller sequence generationformula. For example, the to-be-sent pilot sequence may be generatedaccording to an order-1 or order-2 Reed-Muller sequence generationformula, or may be generated according to a higher-order Reed-Mullersequence generation formula.

Optionally, in this embodiment of this application, the terminal devicemay obtain the to-be-sent pilot sequence from a pilot sequence set,where the pilot sequence set may include at least two Reed-Mullersequences. A pilot in the pilot sequence set may be generated accordingto a Reed-Muller sequence formula and is stored in the terminal device.The pilot may be stored in a form of a table.

The to-be-sent pilot sequence may be selected from the pilot sequenceset randomly or based on a pilot index. Certainly, the pilot index maybe called by another name such as a pilot number by a person skilled inthe art. The pilot index may be used as a basis for selecting a pilotsequence from a pilot sequence set and may be in various forms. Forexample, the pilot index may be generated by using a random numbergenerator. For example, different initial values may be set for apseudo-noise (PN) sequence to generate different random numbersequences, so that the pilot index is obtained accordingly. A possiblemethod for selecting the initial value is based on at least one of anidentifier of the terminal, a system frame number, a timeslot number,and a cell identifier. The system frame number may be a sequence numberof a frame in which a target pilot sequence is to be transmitted, thetimeslot number may be a number of a timeslot in which the target pilotsequence is to be transmitted, and the cell identifier may be anidentifier of a cell in which the terminal device is located.

Optionally, pilot sequence sets corresponding to various pilot sequencelengths may be pre-stored in the terminal device. After a length of theto-be-sent pilot sequence is determined, the to-be-sent pilot sequencemay be selected from a pilot sequence set corresponding to the length.

Optionally, as shown in FIG. 3, the method 200 may further include step220: A network device sends first indication information, and optionallysends the first indication information to the terminal device, and theterminal device performs a corresponding receiving action, where thefirst indication information is used to indicate a length of theto-be-sent pilot sequence. In this way, the terminal device maydetermine the length of the to-be-sent pilot sequence based onindication of the first indication information.

A longer length of a pilot sequence indicates a larger quantity ofpilots that can be selected and a larger quantity of terminals that canbe distinguished. However, corresponding resource overheads anddetection complexity are also increased. Therefore, a pilot sequencelength may be adjusted depending on different application scenarios. Forexample, the pilot sequence length may be adjusted based on a timesegment. For example, there is a smaller quantity of users at night, anda shorter sequence length may be used.

Optionally, in this embodiment of this application, the length 2^(m) ofthe to-be-sent pilot sequence may be determined first, and then thematrix p of m rows and m columns and the vector b of m rows areselected. An order-2 Reed-Muller sequence is obtained as the to-be-sentpilot sequence according to the formula 2 by using the matrix p and thevector b.

Optionally, after the length of the pilot sequence is determined, thematrix p may be selected from a matrix p set corresponding to thelength, where the matrix p set includes a plurality of matrices p of mrows and m columns; and the vector b of m rows may be selected from avector b set corresponding to the length, where the vector b setincludes a plurality of vectors b of m rows.

Optionally, the matrix p may be selected from the matrix p set and thevector b may be selected from the vector b set based on a pilot index.The pilot index may be generated by using a random number generator. Forexample, different initial values may be set for a PN sequence togenerate different random number sequences, so that the pilot index isobtained accordingly. A possible method for selecting the initial valueis based on at least one of an identifier of the terminal, a systemframe number, a timeslot number, and a cell identifier. The system framenumber may be a sequence number of a frame in which a target pilotsequence is to be transmitted, the timeslot number may be a number of atimeslot in which the target pilot sequence is to be transmitted, andthe cell identifier may be an identifier of a cell in which the terminaldevice is located.

Optionally, a same pilot index may be used to select the matrix p fromthe matrix p set and the vector b from the vector b set. Certainly,different pilot indexes may be used to select the matrix p from thematrix p set and the vector b from the vector b set.

Optionally, as shown in FIG. 3, the method 200 may further include step230: The network device sends second indication information, andoptionally sends the second indication information to the terminaldevice, and the terminal device performs a corresponding receivingaction, where the second indication information is used to indicate amatrix p set and/or a vector b set. For example, the terminal device maypre-store a plurality of matrix p sets and a plurality of vector b sets.The network device may notify the terminal device of an index of amatrix p set needed to be used and an index of a vector b set needed tobe used. The terminal device selects the matrix p set from the pluralityof matrix p sets based on the index of the matrix p set notified by thenetwork device, and selects the vector b set from the plurality ofvector b sets based on the index of the vector b set notified by thenetwork device, so as to select the matrix p from the selected matrix pset and select the vector b from the selected vector b set.

Optionally, information for indicating the matrix p set and informationfor indicating the vector b set may be carried in different indicationinformation. The different indication information may be carried indifferent fields of a same message, or may be carried in differentmessages.

Optionally, after determining the matrix p and the vector b, theterminal device may generate the pilot sequence according to theforegoing formula 2. Alternatively, pilot sequences corresponding to allmatrices p and all vectors b may be pre-stored in the terminal device,and the terminal device may find the corresponding pilot sequence basedon the matrix p and the vector b. The pre-stored pilot sequences mayalso be generated according to the foregoing formula 2.

It should be understood that, both step 220 and step 230 shown in FIG. 3are optional operations of the method 200. The method 200 may includestep 220 but does not include step 230, or may include step 230 but doesnot include step 220, or may include step 220 and step 230. For example,when step 220 is included but step 230 is not included, the terminaldevice may search, based on the length of the to-be-sent pilot sequenceindicated by the first indication information, information stored in theterminal device for the matrix p set and the vector b set that arecorresponding to the length of the pilot sequence. For example, whenstep 230 is included but step 220 is not included, the terminal devicemay determine the length of the to-be-sent pilot sequence based on asize of a to-be-sent time-frequency resource, and select the matrix pfrom the matrix p set indicated by the second indication information andselect the vector b from the vector b set indicated by the secondindication information.

Optionally, the foregoing first indication information and secondindication information may be sent by using a same broadcast message, ormay be sent by using different broadcast messages.

Optionally, the to-be-sent pilot sequence is a pilot sequence for userstatus detection, for example, an activity detection reference signal(ADRS). In this case, the terminal device sends the to-be-sent pilotsequence on partial bandwidth of available bandwidth.

In this embodiment of this application, a pilot used for grant-freetransmission may include an ADRS and a demodulation reference signal(DMRS). The ADRS is used for user status detection, may be implementedby using a Reed-Muller sequence, and is sent only on some sub-bands. TheDMRS is used for channel estimation for data demodulation. Increasing aquantity of pilots by using sequence grouping can allow partialcollision between different pilots. Transmission of the ADRS and theDMRS is shown in FIG. 4, but is not limited thereto.

Optionally, the ADRS may be in one-to-one correspondence with the DMRS.

In this embodiment of this application, separating the pilots of twofunctions can reduce overall pilot resource overheads and channelestimation complexity.

Step 240. The terminal device sends the to-be-sent pilot sequence, andoptionally sends the to-be-sent pilot sequence to the network device.

Optionally, in this embodiment of this application, when a size of atime-frequency resource occupied by the pilot sequence is smaller thanthat of a to-be-used time-frequency resource, length compensationprocessing may be performed on the pilot sequence, to be specific, somebits of the pilot sequence may be repeatedly carried on redundanttime-frequency resources.

Step 250. The network device obtains a received signal, where thereceived signal includes a pilot sequence sent by at least one terminaldevice, the pilot sequence is a Reed-Muller sequence, and the at leastone terminal device includes the foregoing terminal device.

Step 260. The network device obtains the pilot sequence sent by the atleast one terminal device from the received signal.

It should be understood that, although for ease of illustration, FIG. 3shows only one terminal device, this application is not limited thereto.In other words, there may be a plurality of terminal devices that send apilot sequence to the network device on a same time-frequency resource.After obtaining a received signal that includes pilot sequences of theplurality of terminal devices, the network device may separately obtaina pilot sequence sent by each terminal device from the received signal.

Specifically, it is assumed that the pilot sequence received by thenetwork device is obtained by superposing pilot sequences sent by aplurality of active terminal devices:

${y = {{\sum\limits_{i = 1}^{s}{h_{i}\varphi_{p_{i},b_{i}}}} + n_{p_{i},b_{i}}}},$

where

h_(i) is a channel gain of a user i, S indicates a quantity of activeusers, and n indicates a noise signal.

After receiving the superimposed pilot sequence, the network device maydetect the pilot sequence to obtain the pilot sequence sent by eachterminal device.

The following describes an optional detection method 300 with referenceto FIG. 5.

A pilot sequence is detected by using S steps. In each step, a status ofone active user is estimated and channel estimation is performed. It isassumed that y₁=y, and a k^(th) step is as follows.

Step 310. Perform interleaving and multiplication on a received signalY:

${{{y_{k}\left( {a \oplus e} \right)}\overset{\_}{y_{k}(a)}} = {{\frac{1}{2^{m}}{\sum\limits_{i = 1}^{S}{{h_{i}}^{2}\left( {- 1} \right)^{b_{i}^{T}e}\left( {- 1} \right)^{{({p_{i}e})}^{T_{a}}}}}} + {chirps}}},$

where

chirps are cross items between a noise and different p_(i)'s, a is a bitvector of a length m and has a total of 2^(m) values, e is a unit vectorof the length m, a quantity of possible values of e is m, y_(k)(a)represents an element at a corresponding location of a vector y_(k),y_(k)(a⊕e) is equivalent to interleaving y_(k)(a), y_(k)(a⊕e)y_(k)(a)means that the interleaved vector is multiplied by y_(k)(a), andy_(k)(a) means conjugation of y_(k)(a). A value obtained afterinterleaving and multiplication is equivalent to a value on the rightside of the equation.

For example, when m=2, a has 2^(m)=4 possible values expressed in binarynotation as 00, 01, 10, and 11, and e has 2 possible values expressed inbinary notation as 10 and 01. In the foregoing equation, y_(k)(a)represents the element at the corresponding location of the vectory_(k). For example, y_(k)(00) represents a first element, y_(k)(01)represents a second element, and so on. In the foregoing equation, a⊕emeans that bitwise modulo-2 addition is performed on a and e. When e=10and a is 00, 01, 10, or 11, a⊕e is 10, 11, 00, or 01. Therefore, y(a⊕e)is equivalent to interleaving y(a). When e=10, y_(k)(a⊕e)y_(k)(a) meansthat an element in a vector (y_(k)(10), y_(k)(11), y_(k)(00), andy_(k)(01)) is multiplied by an element at a corresponding location in avector (y_(k)(00), y_(k)(01), y_(k)(10), and y_(k)(11)), that is,(y_(k)(10)y_(k)(00), y_(k)(11)y_(k)(01), y_(k)(00)y_(k)(10), andy_(k)(01)y_(k)(11)).

Step 320. Perform Hadamard transform on a vector obtained throughinterleaving and multiplication to obtain p_(i).

Specifically, a length of the vector is 2^(m), and therefore a length ofa vector obtained after transform is also 2^(m). From 2^(m) values, anelement having maximum amplitude is found, and a number of the elementis a column of p_(i). When m=2 and e=10, a vector of a length 4 isobtained after Hadamard transform is performed. If a first element hasmaximum amplitude, a first column of p_(i) is 00; if a second elementhas maximum amplitude, a first column of p_(i) is 01, and so on. Whene=01, a value of a second column of p_(i) may be obtained by using asame method.

p_(i) may be restored by repeating this process. Complexity of theoperation is O(m2^(2m)), that is, the complexity is in direct proportionto m2^(2m).

Step 330. Perform vector multiplication on a signal y_(k)(a):

${{y_{k}(a)}{\overset{\_}{\varphi_{P_{1},0}}(a)}} = {{\frac{1}{2^{m}}{h_{i}\left( {- 1} \right)}^{{{wt}{(b_{i})}}^{T_{a}}}} + {{chirps}.}}$

A peak value is generated at b_(i) when Hadamard transform is performedon the right side of the foregoing equation. Accordingly, p_(i) ^(b)^(i) may be restored. Complexity of the operation is O(2^(2m)), that is,the complexity is in direct proportion to 2^(2m).

Step 340. Determine a pilot sequence of a user, determine a channel gaincorresponding to a terminal device i through optimization problemresolution, and update the received signal.

The pilot sequence of the user is obtained based on p_(i) and b_(i) byusing the foregoing formula 2.

The channel gain corresponding to the terminal device i is determinedthrough optimization problem resolution:

min{(y _(k) −h _(i)ϕ_(P) _(i) _(,b) _(i) )²}.

The received signal is updated:

y _(k+1) =y _(k) −h _(i)ϕ_(P) _(i) _(,b) _(i) .

A base station completes user status detection and channel estimation byusing the foregoing algorithm, thereby implementing an important step ofgrant-free access.

Optionally, in this embodiment of this application, the terminal devicefurther sends data to a network device.

The network device may send a feedback message to the terminal devicebased on a decoding status of the data. The feedback message is used toindicate whether the pilot sequence is detected and whether the data issuccessfully decoded.

There may be a plurality of results for sending the data by the terminaldevice after the terminal device accesses the network device in agrant-free mode. A first result is that the network device detects thepilot sequence and successfully decodes the data. A second result isthat the network device detects the pilot sequence but unsuccessfullydecodes the data. A third result is that the network device detects nopilot sequence. In the first case, the network device may send anacknowledgment (ACK) feedback message to the terminal device. In thesecond case, the network device may send a negative acknowledgment(NACK) feedback message to the terminal device. When receiving the NACKsent by the network device, the terminal device may retransmit the datato the network device.

It should be understood that, in this embodiment of this application,the sequence generated according to the formula 1, the formula 2, or aformula of a higher order is referred to as a Reed-Muller sequence, ormay be called by another name. Any sequence that is generated accordingto the formula 1, the formula 2, or a corresponding variant formula iswithin the protection scope of this application.

FIG. 6 is a schematic flowchart of an information transmission method400 according to an embodiment of this application. Optionally, themethod 400 may be used for grant-free transmission.

As shown in FIG. 6, the method includes the following steps.

Step 410. A terminal device obtains a to-be-sent pilot sequence, wherethe to-be-sent pilot sequence is a sequence generated according to aformula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.

Optionally, the terminal device obtains the to-be-sent pilot sequencefrom a pilot sequence set, where the pilot sequence set includes atleast two sequences. A pilot sequence in the pilot sequence set may be asequence generated according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}$

and is stored in the terminal device.

The to-be-sent pilot sequence may be selected from the pilot sequenceset randomly or based on a pilot index. For example, the pilot index maybe generated by using a random number generator. For example, differentinitial values may be set for a pseudo-noise (Pseudo-noise, PN) sequenceto generate different random number sequences, so that the pilot indexis obtained accordingly. A possible method for selecting the initialvalue is based on at least one of an identifier of the terminal, asystem frame number, a timeslot number, and a cell identifier. Thesystem frame number may be a sequence number of a frame in which atarget pilot sequence is to be transmitted, the timeslot number may be anumber of a timeslot in which the target pilot sequence is to betransmitted, and the cell identifier may be an identifier of a cell inwhich the terminal device is located.

Optionally, pilot sequence sets corresponding to various pilot sequencelengths may be pre-stored in the terminal device. After the length ofthe to-be-sent pilot sequence is determined, the to-be-sent pilotsequence may be selected from a pilot sequence set corresponding to thelength.

Optionally, as shown in FIG. 6, the method 400 may further include step420: A network device sends first indication information, and optionallysends the first indication information to the terminal device, and theterminal device performs a corresponding receiving action, where thefirst indication information is used to indicate the length of theto-be-sent pilot sequence. In this way, the terminal device maydetermine the length of the to-be-sent pilot sequence based onindication of the first indication information.

Optionally, the terminal device determines the length of the to-be-sentpilot sequence, where the length of the to-be-sent pilot sequence is2^(m) and m is a positive integer; determines the matrix p of m rows andm columns and the vector b of m rows; and generates a sequence as theto-be-sent pilot sequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

Optionally, the terminal device selects the matrix p from a matrix p setcorresponding to m; and selects the vector b from a vector b setcorresponding to m.

The matrix p may be selected from the matrix p set and the vector b maybe selected from the vector b set based on a pilot index. The pilotindex may be generated by using a random number generator. For example,different initial values may be set for a PN sequence to generatedifferent random number sequences, so that the pilot index is obtainedaccordingly. A possible method for selecting the initial value is basedon at least one of an identifier of the terminal, a system frame number,a timeslot number, and a cell identifier. The system frame number may bea sequence number of a frame in which a target pilot sequence is to betransmitted, the timeslot number may be a number of a timeslot in whichthe target pilot sequence is to be transmitted, and the cell identifiermay be an identifier of a cell in which the terminal device is located.

Optionally, a same pilot index may be used to select the matrix p fromthe matrix p set and the vector b from the vector b set. Certainly,different pilot indexes may be used to select the matrix p from thematrix p set and the vector b from the vector b set.

Optionally, as shown in FIG. 6, the method 400 may further include step430: The network device sends second indication information, andoptionally sends the second indication information to the terminaldevice, and the terminal device performs a corresponding receivingaction, where the second indication information is used to indicate amatrix p set and/or a vector b set. For example, the terminal device maypre-store a plurality of matrix p sets and a plurality of vector b sets.The network device may notify the terminal device of an index of amatrix p set needed to be used and an index of a vector b set needed tobe used. The terminal device selects the matrix p set from the pluralityof matrix p sets based on the index of the matrix p set notified by thenetwork device, and selects the vector b set from the plurality ofvector b sets based on the index of the vector b set notified by thenetwork device, so as to select the matrix p from the selected matrix pset and select the vector b from the selected vector b set.

Optionally, information for indicating the matrix p set and informationfor indicating the vector b set may be carried in different indicationinformation. The different indication information may be carried indifferent fields of a same message, or may be carried in differentmessages.

Optionally, after determining the matrix p and the vector b, theterminal device may generate the pilot sequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

Alternatively, pilot sequences corresponding to all matrices p and allvectors b may be pre-stored in the terminal device, and the terminaldevice may find the corresponding pilot sequence based on the matrix pand the vector b. The pre-stored pilot sequences may also be generatedaccording to the foregoing formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

It should be understood that, both step 420 and step 430 shown in FIG. 6are optional operations of the method 400. The method 400 may includestep 420 but does not include step 430, or may include step 430 but doesnot include step 420, or may include step 420 and step 430. For example,when step 420 is included but step 430 is not included, the terminaldevice may search, based on the length of the to-be-sent pilot sequenceindicated by the first indication information, information stored in theterminal device for the matrix p set and the vector b set that arecorresponding to the length of the pilot sequence. For example, whenstep 430 is included but step 420 is not included, the terminal devicemay determine the length of the to-be-sent pilot sequence based on asize of a to-be-sent time-frequency resource, and select the matrix pfrom the matrix p set indicated by the second indication information andselect the vector b from the vector b set indicated by the secondindication information.

Optionally, the foregoing first indication information and secondindication information may be sent by using a same broadcast message, ormay be sent by using different broadcast messages.

Optionally, the matrix in the matrix p set is a binary symmetric matrixwhose diagonal consists of 0s, and each element of the matrix is 0 or 1;and/or the vector in the vector b set is a binary vector, and eachelement of the vector is 0 or 1.

Optionally, the to-be-sent pilot sequence is used for user statusdetection.

Optionally, the terminal device sends the to-be-sent pilot sequence onpartial bandwidth of available bandwidth.

Step 440. The terminal device sends the to-be-sent pilot sequence.

Step 450. The network device obtains a received signal, where thereceived signal includes a pilot sequence sent by at least one terminaldevice, and the pilot sequence is a sequence generated according to aformula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1. The at least one terminal deviceincludes the foregoing terminal device.

Step 460. The network device obtains the pilot sequence sent by the atleast one terminal device from the received signal.

It should be understood that, although for ease of illustration, FIG. 6shows only one terminal device, this application is not limited thereto.In other words, there may be a plurality of terminal devices that send apilot sequence to the network device on a same time-frequency resource.After obtaining a received signal that includes pilot sequences of theplurality of terminal devices, the network device may separately obtaina pilot sequence sent by each terminal device from the received signal.

Optionally, in this embodiment of this application, the terminal devicefurther sends data to the network device.

There may be a plurality of results for sending the data by the terminaldevice after the terminal device accesses the network device in agrant-free mode. A first result is that the network device detects thepilot sequence and successfully decodes the data. A second result isthat the network device detects the pilot sequence but unsuccessfullydecodes the data. A third result is that the network device detects nopilot sequence. In the first case, the network device may send anacknowledgment (ACK) feedback message to the terminal device. In thesecond case, the network device may send a negative acknowledgment(NACK) feedback message to the terminal device. When receiving the NACKsent by the network device, the terminal device may retransmit the datato the network device.

FIG. 7 is a schematic block diagram of a terminal device 700 accordingto an embodiment of this application. As shown in FIG. 7, the terminaldevice 700 includes: an obtaining unit 710, configured to obtain ato-be-sent pilot sequence, where the to-be-sent pilot sequence is aReed-Muller sequence; and a sending unit 720, configured to send theto-be-sent pilot sequence.

Optionally, the terminal device is applied to grant-free transmission.

Optionally, the to-be-sent pilot sequence is generated according to aReed-Muller sequence generation formula.

Optionally, the to-be-sent pilot sequence is an order-2 Reed-Mullersequence generated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.

Optionally, the obtaining unit 710 is specifically configured to: obtainthe to-be-sent pilot sequence from a pilot sequence set, where the pilotsequence set includes at least two Reed-Muller sequences.

Optionally, the obtaining unit 710 is specifically configured to:determine the length of the to-be-sent pilot sequence, where the lengthof the to-be-sent pilot sequence is 2^(m) and m is a positive integer;determine the matrix p of m rows and m columns and the vector b of mrows; and

generate an order-2 Reed-Muller sequence as the to-be-sent pilotsequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

Optionally, as shown in FIG. 7, the terminal device 700 further includesa receiving unit 730, configured to receive first indication informationsent by a network device, where the first indication information is usedto indicate the length of the to-be-sent pilot sequence. The obtainingunit 710 is specifically configured to determine the length of theto-be-sent pilot sequence based on indication of the first indicationinformation.

Optionally, the obtaining unit 710 is specifically configured todetermine the length of the to-be-sent pilot sequence based on a size ofa to-be-used time-frequency resource.

Optionally, the matrix p is a binary symmetric matrix.

Optionally, the obtaining unit 710 is specifically configured to: selectthe matrix p from a matrix p set corresponding to m; and select thevector b from a vector b set corresponding to m.

Optionally, the matrix p in the matrix p set is a binary symmetricmatrix whose diagonal consists of 0s, and each element of the matrix pis 0 or 1; and/or the vector b in the vector b set is a binary vector,and each element of the vector b is 0 or 1.

Optionally, the obtaining unit 710 is specifically configured to:generate a pilot index based on at least one of an identifier of theterminal device, a system frame number, a timeslot number, and a cellidentifier; select, based on the pilot index, the matrix p from thematrix p set corresponding to m; and select, based on the pilot index,the vector b from the vector b set corresponding to m.

Optionally, as shown in FIG. 7, the terminal device further includes thereceiving unit 730, configured to receive second indication informationsent by the network device, where the second indication information isused to indicate the matrix p set and/or the vector b set.

Optionally, the to-be-sent pilot sequence is used for user statusdetection.

Optionally, the sending unit 720 is specifically configured to send theto-be-sent pilot sequence on partial bandwidth of available bandwidth.

Optionally, the sending unit 720 is further configured to send data tothe network device.

Optionally, as shown in FIG. 7, the terminal device 700 further includesthe receiving unit 730, configured to receive a feedback message sent bythe network device, where the feedback message is used to indicatewhether the data and the pilot sequence are successfully decoded.Specifically, the receiving unit receives an acknowledgment feedbackmessage sent by the network device, where the acknowledgment feedbackmessage is used to indicate that the pilot sequence is detected and thedata is successfully decoded; or receives a negative acknowledgmentfeedback message sent by the network device, where the negativeacknowledgment feedback message is used to indicate that the pilotsequence is detected but the data is unsuccessfully decoded.

It should be understood that, the terminal device 700 may becorresponding to the terminal device in the method 200, and may have thecorresponding functions of the terminal device in the method 200. Forbrevity, details are not repeated herein.

FIG. 8 is a schematic block diagram of a network device 800 according toan embodiment of this application. As shown in FIG. 8, the networkdevice 800 includes: a receiving unit 810, configured to obtain areceived signal, where the received signal includes a pilot sequence ofat least one terminal device, and the pilot sequence is a Reed-Mullersequence; and an obtaining unit 820, configured to obtain the pilotsequence of the at least one terminal device from the received signal.

Optionally, the pilot sequence is an order-2 Reed-Muller sequencegenerated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.

Optionally, as shown in FIG. 8, the network device 800 further includesa sending unit 830, configured to send first indication information tothe terminal device, where the first indication information is used toindicate a length of a to-be-sent pilot sequence.

Optionally, as shown in FIG. 8, the network device 800 further includesthe sending unit 830, configured to send second indication informationto the terminal device, where the second indication information is usedto indicate a vector b set and/or a matrix p set, the vector b set isused by the terminal device to select the vector b, and the matrix p setis used by the terminal device to select the matrix p.

Optionally, as shown in FIG. 8, the network device 800 further includesthe sending unit 830. The receiving unit 810 is further configured todetect, based on a pilot sequence of each terminal device, data sent bythe terminal device. The sending unit 830 is further configured to: sendan acknowledgment feedback message to the terminal device when the datais successfully decoded; or send a negative acknowledgment feedbackmessage to the terminal device when the data is unsuccessfully decoded.

It should be understood that, the network device 800 may becorresponding to the network device in the method 200, and may have thecorresponding functions of the network device in the method 200. Forbrevity, details are not repeated herein.

FIG. 9 is a schematic block diagram of a terminal device 900 accordingto an embodiment of this application. As shown in FIG. 9, the terminaldevice 900 includes a processor 910, a memory 920, a transceiver 930,and a bus system 940. The memory 920 is configured to store a programinstruction. The processor 910 may invoke the program instruction storedin the memory 920. The processor 910, the memory 920, and thetransceiver 930 are connected by using the bus system 940.

The processor 910 is configured to invoke the program instruction storedin the memory 920, to perform the following operations: obtaining ato-be-sent pilot sequence, where the to-be-sent pilot sequence is aReed-Muller sequence; and controlling the transceiver 930 to send theto-be-sent pilot sequence.

Optionally, the terminal device 900 is applied to grant-freetransmission.

Optionally, the to-be-sent pilot sequence is generated according to aReed-Muller sequence generation formula.

Optionally, the to-be-sent pilot sequence is an order-2 Reed-Mullersequence generated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where 2^(m) is a length of the pilot sequence; p is a matrix of m rowsand m columns; b is a vector of m rows; a is a bit vector with a lengthof m and consisting of 0s and 1s, has a total of 2^(m) possible values,and is corresponding to 2^(m) elements of the pilot sequence; and i²=−1.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperation: obtaining the to-be-sent pilot sequence from a pilot sequenceset, where the pilot sequence set includes at least two Reed-Mullersequences.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperations: determining the length of the to-be-sent pilot sequence,where the length of the to-be-sent pilot sequence is 2^(m) and m is apositive integer; determining the matrix p of m rows and m columns andthe vector b of m rows; and generating an order-2 Reed-Muller sequenceas the to-be-sent pilot sequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperations: controlling the transceiver 930 to receive first indicationinformation sent by a network device, where the first indicationinformation is used to indicate the length of the to-be-sent pilotsequence; and determining the length of the to-be-sent pilot sequencebased on indication of the first indication information.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperation: determining the length of the to-be-sent pilot sequence basedon a size of a to-be-used time-frequency resource.

Optionally, the matrix p is a binary symmetric matrix.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperations: selecting the matrix p from a matrix p set corresponding tom; and selecting the vector b from a vector b set corresponding to m.

Optionally, the matrix p in the matrix p set is a binary symmetricmatrix whose diagonal consists of 0s, and each element of the matrix pis 0 or 1; and/or the vector b in the vector b set is a binary vector,and each element of the vector b is 0 or 1.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperations: generating a pilot index based on at least one of anidentifier of the terminal device, a system frame number, a timeslotnumber, and a cell identifier; selecting, based on the pilot index, thematrix p from the matrix p set corresponding to m; and selecting, basedon the pilot index, the vector b from the vector b set corresponding tom.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperation: controlling the transceiver 930 to receive second indicationinformation sent by the network device, where the second indicationinformation is used to indicate the matrix p set and/or the vector bset.

Optionally, the to-be-sent pilot sequence is used for user statusdetection.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperation: sending the to-be-sent pilot sequence on partial bandwidth ofavailable bandwidth.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperation: controlling the transceiver 930 to send data to the networkdevice.

Optionally, the processor 910 is configured to invoke the programinstruction stored in the memory 920, to perform the followingoperation: controlling the transceiver 930 to receive a feedback messagesent by the network device, where the feedback message is used toindicate whether the data and the pilot sequence are successfullydecoded.

It should be understood that, the terminal device 900 may becorresponding to the terminal device in the method 200, and may have thecorresponding functions of the terminal device in the method 200. Forbrevity, details are not repeated herein.

FIG. 10 is a schematic block diagram of a network device 1000 accordingto an embodiment of this application. As shown in FIG. 12, the networkdevice 1000 includes a processor 1010, a memory 1020, a transceiver1030, and a bus system 1040. The memory 1020 is configured to store aprogram instruction. The processor 1010 may invoke the programinstruction stored in the memory 1020. The processor 1010, the memory1020, and the transceiver 1030 are connected by using the bus system1040.

The processor 1010 is configured to invoke the program instructionstored in the memory 1020, to perform the following operations:controlling the transceiver 1030 to obtain a received signal, where thereceived signal includes a pilot sequence of at least one terminaldevice, and the pilot sequence is a Reed-Muller sequence; and obtainingthe pilot sequence of the at least one terminal device from the receivedsignal.

Optionally, the pilot sequence is an order-2 Reed-Muller sequencegenerated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.

Optionally, the processor 1010 is configured to invoke the programinstruction stored in the memory 1020, to perform the followingoperation: controlling the transceiver 1030 to send first indicationinformation to the terminal device, where the first indicationinformation is used to indicate a length of a to-be-sent pilot sequence.

Optionally, the processor 1010 is configured to invoke the programinstruction stored in the memory 1020, to perform the followingoperation: controlling the transceiver 1030 to send second indicationinformation to the terminal device, where the second indicationinformation is used to indicate a vector b set and/or a matrix p set,the vector b set is used by the terminal device to select the vector b,and the matrix p set is used by the terminal device to select the matrixp.

The processor 1010 is configured to invoke the program instructionstored in the memory 1020, to perform the following operations:detecting, based on a pilot sequence of each terminal device, data sentby the terminal device; and when the data is successfully decoded,controlling the transceiver 1030 to send an acknowledgment feedbackmessage to the terminal device, or when the data is unsuccessfullydecoded, controlling the transceiver 1030 to send a negativeacknowledgment feedback message to the terminal device.

It should be understood that, the network device 1000 may becorresponding to the network device in the method 200, and may have thecorresponding functions of the network device in the method 200. Forbrevity, details are not repeated herein.

FIG. 11 is a schematic block diagram of a terminal device 1100 accordingto an embodiment of this application. As shown in FIG. 13, the terminaldevice 1100 includes: an obtaining unit 1110, configured to obtain ato-be-sent pilot sequence, where the to-be-sent pilot sequence is asequence generated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1; and a sending unit 1120, configured tosend the to-be-sent pilot sequence.

Optionally, the obtaining unit 1110 is configured to: obtain theto-be-sent pilot sequence from a pilot sequence set, where the pilotsequence set includes at least two sequences.

Optionally, the obtaining unit 1110 is specifically configured to:determine the length of the to-be-sent pilot sequence, where the lengthof the to-be-sent pilot sequence is 2^(m) and m is a positive integer;determine the matrix p of m rows and m columns and the vector b of mrows; and generate a sequence as the to-be-sent pilot sequence accordingto the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

Optionally, as shown in FIG. 13, the terminal device 1110 furtherincludes a receiving unit 1130, configured to receive first indicationinformation sent by a network device, where the first indicationinformation is used to indicate the length of the to-be-sent pilotsequence.

Optionally, the obtaining unit 1110 is specifically configured to:select the matrix p from a matrix p set corresponding to m; and selectthe vector b from a vector b set corresponding to m.

Optionally, the matrix in the matrix p set is a binary symmetric matrixwhose diagonal consists of 0s, and each element of the matrix is 0 or 1;and/or the vector in the vector b set is a binary vector, and eachelement of the vector is 0 or 1.

Optionally, the obtaining unit 1110 is specifically configured to:generate a pilot index based on at least one of an identifier of theterminal device, a system frame number, a timeslot number, and a cellidentifier; select, based on the pilot index, the matrix p from thematrix p set corresponding to m; and select, based on the pilot index,the vector b from the vector b set corresponding to m.

Optionally, as shown in FIG. 13, the terminal device 1110 furtherincludes the receiving unit 1130, configured to receive secondindication information sent by the network device, where the secondindication information is used to indicate the matrix p set and/or thevector b set.

Optionally, the to-be-sent pilot sequence is used for user statusdetection.

Optionally, the sending unit 1120 sends the to-be-sent pilot sequence onpartial bandwidth of available bandwidth.

It should be understood that, the terminal device 1100 may becorresponding to the terminal device in the method 400, and may have thecorresponding functions of the terminal device in the method 400. Forbrevity, details are not repeated herein.

FIG. 12 is a schematic block diagram of a network device 1200 accordingto an embodiment of this application. As shown in FIG. 12, the networkdevice 1200 includes a receiving unit 1210 and an obtaining unit 1220.The receiving unit 1210 is configured to obtain a received signal, wherethe received signal includes a pilot sequence sent by at least oneterminal device, and the pilot sequence is a sequence generatedaccording to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and Is, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1. The obtaining unit 1220 is configuredto obtain the pilot sequence sent by the at least one terminal devicefrom the received signal.

Optionally, as shown in FIG. 12, the network device 1200 furtherincludes a sending unit 1230, configured to send first indicationinformation to the terminal device, where the first indicationinformation is used to indicate a length of a to-be-sent pilot sequence.

Optionally, as shown in FIG. 12, the network device 1200 furtherincludes the sending unit 1230, configured to send second indicationinformation to the terminal device, where the second indicationinformation is used to indicate at least one of a vector b set and amatrix p set, the vector b set is used by the terminal device to selectthe vector b, and the matrix p set is used by the terminal device toselect the matrix p.

It should be understood that, the network device 1200 may becorresponding to the network device in the method 400, and may have thecorresponding functions of the network device in the method 400. Forbrevity, details are not repeated herein.

FIG. 13 is a schematic block diagram of a terminal device 1300 accordingto an embodiment of this application. As shown in FIG. 13, the terminaldevice 1300 includes a processor 1310, a memory 1320, a transceiver1330, and a bus system 1340. The memory 1320 is configured to store aprogram instruction. The processor 1310 may invoke the programinstruction stored in the memory 1320. The processor 1310, the memory1320, and the transceiver 1330 may be connected by using the bus system1340.

The processor 1310 is configured to invoke the program instructionstored in the memory 1320, to perform the following operations:obtaining a to-be-sent pilot sequence, where the to-be-sent pilotsequence is a sequence generated according to a formula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1; and controlling the transceiver 1330to send the to-be-sent pilot sequence.

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperation: obtaining the to-be-sent pilot sequence from a pilot sequenceset, where the pilot sequence set includes at least two sequences.

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperations: determining the length of the to-be-sent pilot sequence,where the length of the to-be-sent pilot sequence is 2^(m) and m is apositive integer; determining the matrix p of m rows and m columns andthe vector b of m rows; and generating a sequence as the to-be-sentpilot sequence according to the formula

${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperation: controlling the transceiver 1330 to receive first indicationinformation sent by a network device, where the first indicationinformation is used to indicate the length of the to-be-sent pilotsequence.

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperations: selecting the matrix p from a matrix p set corresponding tom; and selecting the vector b from a vector b set corresponding to m.

Optionally, the matrix in the matrix p set is a binary symmetric matrixwhose diagonal consists of 0s, and each element of the matrix is 0 or 1;and/or the vector in the vector b set is a binary vector, and eachelement of the vector is 0 or 1.

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperations: generating a pilot index based on at least one of anidentifier of the terminal device, a system frame number, a timeslotnumber, and a cell identifier; selecting, based on the pilot index, thematrix p from the matrix p set corresponding to m; and selecting, basedon the pilot index, the vector b from the vector b set corresponding tom.

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperation: controlling the transceiver 1330 to receive second indicationinformation sent by the network device, where the second indicationinformation is used to indicate the matrix p set and/or the vector bset.

Optionally, the to-be-sent pilot sequence is used for user statusdetection.

Optionally, the processor 1310 is configured to invoke the programinstruction stored in the memory 1320, to perform the followingoperation: controlling the transceiver 1330 to send the to-be-sent pilotsequence on partial bandwidth of available bandwidth.

It should be understood that, the terminal device 1300 may becorresponding to the terminal device in the method 400, and may have thecorresponding functions of the terminal device in the method 400. Forbrevity, details are not repeated herein.

FIG. 14 is a schematic block diagram of a network device 1400 accordingto an embodiment of this application. As shown in FIG. 14, the networkdevice 1400 includes a processor 1410, a memory 1420, a transceiver1430, and a bus system 1440. The memory 1420 is configured to store aprogram instruction. The processor 1410 may invoke the programinstruction stored in the memory 1420. The processor 1410, the memory1420, and the transceiver 1430 may be connected by using the bus system1440.

The processor 1410 is configured to invoke the program instructionstored in the memory 1420, to perform the following operations:controlling the transceiver 1430 to obtain a received signal, where thereceived signal includes a pilot sequence sent by at least one terminaldevice, and the pilot sequence is a sequence generated according to aformula

${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$

where a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1; and obtaining the pilot sequence sentby the at least one terminal device from the received signal.

Optionally, the processor 1410 is configured to invoke the programinstruction stored in the memory 1420, to perform the followingoperation: controlling the transceiver 1430 to send first indicationinformation to the terminal device, where the first indicationinformation is used to indicate a length of a to-be-sent pilot sequence.

Optionally, the processor 1410 is configured to invoke the programinstruction stored in the memory 1420, to perform the followingoperation: controlling the transceiver 1430 to send second indicationinformation to the terminal device, where the second indicationinformation is used to indicate at least one of a vector b set and amatrix p set, the vector b set is used by the terminal device to selectthe vector b, and the matrix p set is used by the terminal device toselect the matrix p.

It should be understood that, the network device 1400 may becorresponding to the network device in the method 400, and may have thecorresponding functions of the network device in the method 400. Forbrevity, details are not repeated herein.

The apparatus in the embodiments of this application may be afield-programmable gate array (FPGA), an application-specific integratedcircuit (ASIC), a system on chip (SoC), a central processing unit (CPU),a network processor (NP), a digital signal processing circuit (DSP), amicrocontroller unit (MCU), a programmable logic device (PLD), oranother integrated chip.

A person of ordinary skill in the art may be aware that, units andalgorithm steps in the examples described in combination with theembodiments disclosed in this specification may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forease of description and brevity, for a detailed working process of theforegoing system, apparatus, and unit, reference may be made to acorresponding process in the foregoing method embodiments. Details arenot repeated herein.

In the several embodiments provided in this application, it should beunderstood that, the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electrical, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate. Parts displayed as units may or may not be physical units, andmay be located in one position or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected depending onactual requirements to achieve the objectives of the solutions of theembodiments.

In addition, the functional units in the embodiments of this applicationmay be integrated into one processing unit, or each of the units mayexist alone physically, or at least two units may be integrated into oneunit.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of this application essentially,or the part contributing to the prior art, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesseveral instructions for instructing a computer device (which may be apersonal computer, a server, a network device, or the like) to performall or some of the steps of the methods described in the embodiments ofthis application. The foregoing storage medium includes any medium thatcan store program code, such as a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

What is claimed is:
 1. An information transmission method, comprising:obtaining, by a terminal device, a to-be-sent pilot sequence, whereinthe to-be-sent pilot sequence is a Reed-Muller sequence; and sending, bythe terminal device, the to-be-sent pilot sequence.
 2. The methodaccording to claim 1, wherein the to-be-sent pilot sequence is generatedaccording to a Reed-Muller sequence generation formula.
 3. The methodaccording to claim 2, wherein the to-be-sent pilot sequence is anorder-2 Reed-Muller sequence generated according to a formula${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$wherein a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.
 4. The method according to claim 3,wherein obtaining, by a terminal device, a to-be-sent pilot sequencecomprises: determining a length of the to-be-sent pilot sequence,wherein the length of the to-be-sent pilot sequence is 2^(m);determining a matrix p of m rows and m columns and a vector b of m rows;and generating an order-2 Reed-Muller sequence as the to-be-sent pilotsequence according to the formula${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$5. The method according to claim 4, wherein the matrix p is a binarysymmetric matrix.
 6. A terminal device, comprising: a processor,configured to obtain a to-be-sent pilot sequence, wherein the to-be-sentpilot sequence is a Reed-Muller sequence; and a transceiver, configuredto send the to-be-sent pilot sequence.
 7. The terminal device accordingto claim 6, wherein the to-be-sent pilot sequence is generated accordingto a Reed-Muller sequence generation formula.
 8. The terminal deviceaccording to claim 7, wherein the to-be-sent pilot sequence is anorder-2 Reed-Muller sequence generated according to a formula${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$wherein a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.
 9. The terminal device according toclaim 8, wherein the processor is configured to: determine a length ofthe to-be-sent pilot sequence, wherein the length of the to-be-sentpilot sequence is 2^(m); determine a matrix p of m rows and m columnsand a vector b of m rows; and generate an order-2 Reed-Muller sequenceas the to-be-sent pilot sequence according to the formula${\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}{i^{{({{2b} + {pb}})}^{T}a}.}}$10. The terminal device according to claim 9, wherein the matrix p is abinary symmetric matrix.
 11. The terminal device according to claim 9,wherein the processor is configured to: select the matrix p from amatrix p set corresponding to m; and select the vector b from a vector bset corresponding to m.
 12. The terminal device according to claim 11,wherein: the transceiver is configured to receive second indicationinformation sent by a network device, wherein the second indicationinformation is used to indicate the matrix p set and/or the vector bset; and the processor is configured to: based on indication of thesecond indication information, select the matrix p from the matrix p setindicated by the second indication information, and select the vector bfrom the vector b set indicated by the second indication information.13. A network device, comprising: a transceiver, configured to obtain areceived signal comprising a pilot sequence of at least one terminaldevice, and the pilot sequence is a Reed-Muller sequence; and aprocessor, configured to obtain the pilot sequence from the receivedsignal.
 14. The network device according to claim 13, wherein the pilotsequence is an order-2 Reed-Muller sequence generated according to aformula${{\varphi_{p,b}(a)} = {\frac{1}{\sqrt{2^{m}}}i^{{({{2b} + {pb}})}^{T}a}}},$wherein a length of the pilot sequence is 2^(m) and m is a positiveinteger; p is a matrix of m rows and m columns; b is a vector of m rows;a is a bit vector with a length of m and consisting of 0s and 1s, has atotal of 2^(m) possible values, and is corresponding to 2^(m) elementsof the pilot sequence; and i²=−1.
 15. The network device according toclaim 14, wherein the transceiver is further configured to: send firstindication information to the terminal device for indicating a length ofa to-be-sent pilot sequence.